Human Erythrocyte on Glycolipids - We will complete studies of the glycosphingolipids (GSL) from erythrocytes of a new phenotype - a weak P antigen. These cells are partially deficient in globoside and trihexosyl ceramide and sialosylparagloboside. We will also complete isolation and analysis of newly described erythrocyte gangliosides. Glycolipids of Human Lymphocytes - The GSL of thymocytes and peripheral blood lymphocytes are similar and differ appreciably from GSL of tonsil lymphocytes. We plan to perform immunofluorescence studies of human blood lymphocytes with purified antibodies to six glycolipids in order to identify functional subpopulations of these cells. Nuclear Magnetic Resonance Studies of Antibody-Hapten Interactions - We will extend our studies of the reactions of purified sheep antibodies with tetra-L-alanine peptides containing methyl groups enriched in 13C, and carry out similar studies with rabbit anti-alanine antibodies. BIBLIOGRAPHIC REFERENCES: Naiki, M. and Marcus, D.M., An immunochemical study of the human blood group P1, P, and Pk glycosphingolipids. Biochemistry 14: 4837, 1975. Stein-Douglas, K.E., Schwarting, G.A., Naiki, M. and Marcus, D.M., Gangliosides as markers for murine lymphocyte subpopulations. J. Exp. Med. 143:822, 1976.